$\dfrac{9}{5} - \dfrac{2}{5} = {?}$
Answer: $ = {\dfrac{9 \times 1}{5 \times 1}} - {\dfrac{2 \times 1}{5 \times 1}} $ $ = {\dfrac{9}{5}} - {\dfrac{2}{5}} $ $ = \dfrac{{9} - {2}}{5} $ $ = \dfrac{7}{5}$